Both the British Medical Association and the American Academy of Pediatrics recommend that circumcision should only be performed for medical reasons. No one has ever described which reasons are actually used, nor measured the morbidity of the procedure. Of 140 boys coming to day-case elective circumcision between the ages of 3 months and 14 years (mean 4.3 years), the commonest cause was a congenital phimosis (42.8%). Four (2.8%) patients required acute readmission postoperatively, and a further 4 developed meatal stenosis, requiring a formal meatotomy. Of 99 patients followed up in detail, 46% vomited, 36% oozed, 19% did not pass urine for more than 12 h and 26% could not wear pants for more than 7 days. Childhood circumcision has an appreciable morbidity, and should not be recommended without a medical reason.